Just got some more info regarding this one
Cores 0-3/4-7 configuration might be either SoC specific or kernel DTS configuration specific. They can really be configured in whatever fashion that they want. It might appear Sony could have done their own configuration with S615 or to this particular device. Looks reasonable since the DTS configuration is device specific so maybe.
It's not just DraStic that is affected, basically every single benchmark shows M4 has a lower scores comparing to S615s average.
I might ask Qualcomm about S615 configuration but I'm pretty sure it's an OEMs thing